SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f28a92930d39cf15e8f6146fd73116d7e1960e2a5db6f0f4e00975917710869b' 
  AND token = 'h/QaWujZuVtGp4uHnRqewYbpmFYdN7ZIbN+HHNW93GM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}